Even though there are great advancements made in the image display technologies such that scanning images can be displayed with higher resolutions and can be viewed in 3D image from different angles to perform more accurate diagnoses. However, the processes of implementing the two-dimensional array probes are still limited by the technical difficulties. One example is the sparse two-dimensional array probe as disclosed in U.S. Pat. No. 5,911,692 and 6,014,897, that generates images of poor beam resolution and that further complicates the image construction processes by applying the transducer data.
The conventional one-dimensional (1D) array probe is arranged in either a linear flat or a curve convex configuration that has been employed in the ultrasound imaging application for years. The image generated by applying the echo data received from the probe is presented as a 2D cross section. The operator can move the probe around to acquire many two-dimensional image slices, and then interpolate these two-dimensional image slices to detect the disease. Some system also provides volume-rendering algorithm for the free hand or motor driven 3D acquisition for carrying out a pathological diagnosis. However, hand movements often introduce signal noises and measurement instability and lead to inaccurate image reconstruction and unreliable diagnoses.
Referring to FIG. 1A for a conventional beam former control for a one-dimensional (1D) array probe. The focusing acoustic beam is controlled to move along a beam scan direction aligned with the element direction to create a two dimensional (2D) image. A timing control circuit (not shown) generates signals for inputting to a time-delay profile generator as shown in FIGS. 1B, and 1C. The delayed transmit pulses are transmitted to the probe elements to emit the ultrasonic waves for transmitting, focusing, and then receiving the reflected signals transmitted through the similar delay profile to form a 1-D image. The beam can be scanned along the element direction with the same profile in linear array, or steered at different angle in phase array configuration to form a 2-D image.
In the past 10 years, many researchers tried the ‘sparse’ 2D array concept. It connects certain number of the 2D array element (e.g. 64×64=4096) into the current system beam forming channels (normally ranges from 64 to 256) with different distribution patterns. This can eliminate the need of a 4096-channel beam former in the ultrasound system. However, the beam resolution in this arrangement will be degraded badly in both azimuth and elevation direction with a significant channel reduction.
In U.S. Pat. No. 5,911,692 entitled “Sparse Two-dimensional Wideband Ultrasound Transducer Arrays”, an ultrasonic imaging system is disclosed. The ultrasonic imaging system employs a thinned array of transducer elements in order to reduce the number of signal processing channels. The transducer elements are reduced in number and then selectively located at grid positions in a pattern, which reduces the side-lobe levels produced by the array. Thinning is accomplished by discretizing the aperture of the transducer array in two steps. First, a continuous aperture is discretized as a set of concentric rings. Then each ring is replaced by a set of spaced transducer elements.
FIG. 1D shows a sparse transducer array 10 disclosed by U.S. Pat. No. 5,911,892 that includes a plurality of transducer elements 12 driven by the transmitter 22. The ultrasonic energy reflected back from the scanned object is converted to an electrical signal by each receiving transducer and applied separately to a receiver through a set of transmit/receive (T/R) switches 26. The digital controller 28 receives command from a human operator to operate the transmitter 22, receiver 24 and switches 26. The controller 28 controls the switches 26 to turn on the transmitter for each of the transducer elements 12. The controller 28 further controls the switches to turn on the transmitter to receive the echo signals at different transducer element with appropriate time delay. The echo signals received by the receiver 24 are then amplified to generate a scan image. However, as discussed above, the sparse 2-D array scanning process cannot provide sufficient resolutions due to the limited channels applied to scan and generate the echo signals.
For these reasons, a need still exists for those of ordinary skill in the art to provide an improved method and system, particularly for 3D medical image scanning and display system to overcome such difficulties. Specifically, it is desirable to provide an improved method and configuration to improve the beam resolution and convenience of image construction for providing high quality and accurate images.